The present invention relates to a column for removing poisons and/or other undesired substances from a liquid mixture. More particularly, the present invention relates to a column for detoxification of blood.
One such column system is disclosed in British Pat. No. 1,482,071. This British Patent discloses a column formed from a biocompatible synthetic polymer material and having inlet and outlet ports for the liquid to be treated. The column is filled with absorptive particulate material, such as activated carbon, located between support means at each end of the column. The construction of the column is said to be such that "non-absorbing dead spaces" between the inlet and outlet ports are minimized.
In a similar vein, U.S. Pat. No. 2,682,268 discloses a column for treating blood comprising a chamber 10 closed at each end by a reticulated screen 12 adapted to hold a granular treatment material 14 in place in the chamber. The chamber 10 is also provided at each end with a suitable end connection 16. The granular treatment material 14, for example, an ion-exchange resin or the like, occupies the volume between the screens 12 to such an extent as to maintain the shape of the body of the column during shipping or handling, but the treatment material does not quite fill the chamber.
Canadian Pat. No. 982,060 discloses a column 10 for removing urea from dialysate solution. The column is filled with at least two layers, one layer being zirconium phosphate 32 and the other being urease in combination with a urease-retaining material 28. The urease-retaining material renders the enzyme urease water-insoluble but allows the urease to retain its ability to enzymatically decompose urea. Magnesium silicate is disclosed as a suitable urease-retaining material. As a liquid containing urea is passed through the urease-retaining layer, the urease converts the urea to ammonium carbonate. The liquid is then passed through the zirconium phosphate layer, which picks up the ammonium ions and replaces them with hydrogen and sodium ions.
Such columns can be used to remove poisons from, for example, blood. However, such columns have certain disadvantages since the same column may not be suitable for use in the treatment of both adults and children. For example, a completely different column capacity is required for detoxification of an adult person than is necessary for a child. Also, it is sometimes necessary to keep the extracorporeal portion of blood considerably smaller with children than with adults.
These column requirements can, of course, be met by using columns of different sizes. However, this requires manufacturing of and maintaining of a stock of such variously sized columns.
Furthermore, when the size of the column is modified, the hydrodynamic conditions in the column are altered. This alteration leads to uncertainty in the results achieved by the treatment and may even substantially complicate the treatment.